1. Field of the Invention
The present invention relates to a flying magnetic head device installed in magneto-optical disk apparatus, etc., and more particularly, to a magnetic head device which is capable of suppressing heat generation by reducing the core loss in a magnetic field generating section provided in the magnetic head device, and which can stably be used even in a high-frequency region by increasing heat-dissipating efficiency against the heat generation.
2. Description of the Related Art
FIG. 7 is a partially exploded perspective view illustrating a conventional flying magnetic head device installed in a magneto-optical disk apparatus; and FIG. 8 is an exploded perspective view illustrating a core assembly held by a slider of the magnetic head device of FIG. 7.
The magnetic head device is composed of a head main body 1 and support members (not shown) for supporting the head main body 1.
The head main body 1 includes a slider 2 and a core assembly 5 (see FIG. 8) held in the slider 2. The slider is formed of a non-magnetic material, such as ceramic or the like, and the bottom side shown in FIG. 7 of the slider 2 constitutes the surface opposed to a recording medium. The top surface side of the slider 2 is supported by the support members, and protrusions 2a, 2b, 2c, 2d, 2e, and 2f are formed thereon. Grooves 3a, 3b, and 3c are formed in the protrusions 2a, 2b, and 2c, respectively. The core assembly is held in the grooves 3a and 3b, and the bottom surface of the core assembly 5 is flush with the surface of the slider 2 opposed to the recording medium.
As shown in FIG. 8, the core assembly 5 is composed of a center core 6, substantially L-shaped side cores 7 joined to both sides of the center core 6, and a back core 11 joined to end surfaces of the center core 6 and the side cores 7. A bobbin 10 around which a coil 9 is wound is fitted onto the center core 6. The center core 6 and the side cores 7 are joined by means of a non-magnetic material 8, such as glass. On the bottom side of the core assembly 5, a pair of magnetic gaps G are formed adjacent to each other on the surface to which the center core 6 and the side cores 7 are opposed. When the core assembly 5 is mounted to the slider 2, as shown in FIG. 7, the back core 11 is fitted into the grooves 3a and 3b.
Numeral 12 indicates a flexure formed of a thin plate spring or the like. A hatching region 12a of the flexure is glued and secured to the top surface 2g surrounded by the protrusions 2a, 2b, 2c, 2d, 2e, and 2f of the slider 2, and the other hatching region 12b of the flexure is glued and secured to the bottom surface of a load beam. The slider 2 is elastically supported by the tip of the load beam through the flexure 12.
The bottom side of the conventional magnetic head device is directed to the surface of a magnetic recording medium, and is pressed into contact with the recording medium by the load beam with a light elastic force. In a magneto-optical disk apparatus, a laser beam is illuminated on the surface of the recording medium from the opposite side of the magnetic head device, and in synchronism therewith, a vertical magnetic field is applied to the magnetic recording medium from the section between the center core and the side cores 7, so that a signal is recorded in the recording medium due to light modulation or magnetic modulation.
When high-density recording is to be performed on the recording medium using the magnetic head device of this type, it is generally required to apply an AC magnetic field of high frequency to the recording medium. Thus, it is necessary to increase the frequency of a current applied to the coil 9.
However, according to the conventional magnetic head device constructed as described above, when the magnetic field of high frequency is to be generated, the heat generated in the core assembly 5 is increased. The heat generation is attributed to core loss (iron loss) such as hysteresis loss and eddy current loss in a magnetic material forming a magnetic path in a magnetic field generating section, i.e., in the center, side and back cores 6, 7 and 11, and further to direct current resistance (copper loss) of the coil 9 provided in the magnetic field generating section. The loss becomes larger in higher frequency bands. In addition, in the magnetic head device shown in FIG. 7, dissipation of the heat generated in the core assembly 5 is poor, and it is difficult for the heat to escape to the outside. Therefore, the core loss due to the heat generation increases, whereby the magnetic field-generating efficiency is further deteriorated.
In addition, in the manufacturing process of the core assembly 5, a magnetic material block having an I-shaped cross-sectional configuration and two L-shaped magnetic material blocks are joined by means of a glass material to form a block having an E-shaped cross-sectional configuration, and the block is cut to have a predetermined thickness to form an E-shaped core 5a shown in FIG. 8 in which the center core 6 and the side cores 7 are joined by means of non-magnetic materials 8.
However, since the manufacturing work of the E-shaped core 5a is complicated, and a large number of steps are required for machining, machining strains are likely to remain on the center and side cores 6 and 7, and stress is likely to act on the glued interface with the non-magnetic materials 8 to impart strain thereon. The magnetic field-generating efficiency is also deteriorated by the machining strain and the gluing strain.